Make the Pepper test run on the mac.

webkit/tools/pepper_test_plugin/README

 This is a test plugin for manual testing of the Pepper plugin API. See
   https://wiki.mozilla.org/Plugins:PlatformIndependentNPAPI
 
 Open the Chrome all.sln solution and rebuild the pepper_test_plugin and
 chrome projects.
 
 To load this plugin in Chrome, use the command line flags:
   --no-sandbox
   --internal-pepper
   --load-plugin=<<<YOUR CHECKOUT ROOT>>\src\webkit\tools\pepper_test_plugin\Debug\pepper_test_plugin.dll
   
 A simple way to launch Chrome with these command line flags is to run the
 generated pepper_test_plugin project.
 
 Note that pepper_test_plugin is not dependent on the chrome project so you
 need to remember to build Chrome separately if necessary.
+
+- Mac Instructions -
+In the pepper_test_plugin.xcodeproj that gets generated in this dir by GYP:
+
+[There isn't a way to add an Xcode Custom Executable via GYP, so you have to do
+this by hand each time the .xcoeproj is generated.  Sorry.]
+
+Right (ctrl)-click 'Executables', then "Add -> New Custom Executable..."
+Call the Executable "Chromium"
+Set the Executable Path to ${BUILT_PRODUCTS_DIR}/Chromium.app/Contents/MacOS/Chromium
+When the Info panel comes up, add these arguments using the '+' button:
+        --no-sandbox
+        --internal-pepper
+        file://${SRCROOT}/test_page.html
+        # Add this if you want Chromium to pause before loading a render view.
+        --renderer-startup-dialog
+        # Add this to run Chromium as a single process.
+        --single-process
+
+Before you run the executable, copy the plugin into the Chromium.app bundle,
+into Chromium.app/Contents/PlugIns.  You might have to create the PlugIns
+directory first.
+
+Once all this is set up, you can use "Build and run" (or cmd-r) in Xcode to
+run the pepper plugin test.
+